Electrolytic assembly

Abstract

An electrolysis assembly operated with an alkaline electrolyte medium. A first region of the assembly comprises an electrolysis cell stack and is adapted to produce a gaseous product from the alkaline electrolyte medium in respective anode and cathode regions of the assembly. A second region of the assembly comprises means for withdrawing gaseous product-rich electrolyte medium from the first region, for introducing gaseous product-lean electrolyte medium into the first region and for separating the produced gaseous product from the electrolyte medium. The means have an inner region for direct contact with the alkaline electrolyte medium, wherein the inner region is at least partially formed by a nickel layer and wherein the nickel layer has a layer thickness of at least 0.1 mm and a nickel content of at least 98 wt.%.

Description

Technical Field

[0001] This invention relates to an electrolysis assembly that operates using an alkaline electrolysis medium. Background Technology

[0002] Electrolysis of water to produce hydrogen is becoming increasingly important in the current era of anthropogenic climate change. For large-scale industrial hydrogen production by electrolysis, two methods are particularly important: proton exchange membrane (PEM) electrolysis and alkaline electrolysis.

[0003] In alkaline electrolysis, the following half-cell reactions occur on the cathode and anode sides.

[0004] Cathode side: 2 H₂O + 2e⁻ - H2 + 2 OH -

[0005] Anode side: 2 OH - O2 + 2e - + H2O

[0006] The end result is that one mole of water forms half a mole of oxygen and one mole of hydrogen. For the reaction to occur in an electrolytic half-cell, hydroxide ions must diffuse from one half-cell to the other through a separator that separates the cathode and anode sides of the electrolytic cell. Especially in alkaline electrolysis, this separator is called a membrane. The membrane functions such that hydroxide ions, as charge carriers, can diffuse between the two half-cell sides, and that the gaseous products generated on the cathode and anode sides are mechanically separated from each other.

[0007] An electrolytic cell has two electrodes (cathode and anode) surrounded by a liquid alkaline electrolyte. The electrolyte used is typically a concentrated aqueous solution of potassium hydroxide or sodium hydroxide. Large-scale industrial electrolyzers consist of multiple electrolytic cells arranged in a stack, one above or one below another, and assembled within a frame or other suitable mechanical device. This design is often referred to as an electrolytic stack.

[0008] To improve the efficiency of the electrolytic cell, the electrolytic system operated by the alkaline electrolysis system is operated at an elevated temperature to increase the conductivity of the electrolyte used and increase the reaction rate.

[0009] The electrolysis system can be basically divided into two regions.

[0010] Electrolysis systems primarily consist of this type of electrolytic reactor. An electrolyte and direct current are introduced into the reactor to produce hydrogen in the cathode space and oxygen in the anode space. The two-phase mixture of the electrolyte and the gaseous products (hydrogen or oxygen) is discharged from the reactor. In addition to electrodes and diaphragms, the electrolytic reactor includes components such as bipolar plates, battery frames, liquid and gas distributors, seals, and pressure-bearing components.

[0011] The second region encompasses the components of the electrolysis system that are primarily fluidly or electrically connected to the electrolytic stack. These components include: loops for the electrolyte medium rich in gaseous products or (mostly / primarily) free of gaseous products; gas-liquid separators; heat exchangers for electrolyte medium temperature management; an electrolyte medium management system including pumps, filters, valves, and piping; and a control system including sensors (flow meters, temperature sensors, pressure sensors) and actuators (control valves). Transformers and rectifiers are also frequently classified into this region. The second region of the electrolysis system is often referred to as the "stack balance" region or simply the BOS region.

[0012] Operating an electrolysis system requires additional system components that connect it to a specific industrial site or independent processing unit. These additional system components include electrical components such as switching devices and harmonic filters; components for oxygen and hydrogen processing (purification, conditioning (dehumidifiers, automatic catalytic recombiners)); cooling units for temperature control (medium coolers and heaters, coolers for rectifiers, gas coolers for gaseous products); desalination units for the water supply; and nitrogen and instrument air supply systems. These components of the equipment are often referred to as "balance-up" components or simply BOP components.

[0013] The electrolyte used in alkaline electrolysis is typically an aqueous solution of potassium hydroxide (KOH) with a concentration of 20% to 30% by weight. The electrolyte is usually circulated in the BOS components of the electrolytic reactor and electrolysis system at temperatures ranging from 60°C to 90°C. Alkaline electrolyzers can operate at atmospheric pressure and positive pressure. The latter operating mode is also known as pressure electrolysis. To maintain pressure in this electrolysis system, the BOS components are typically made of metal. BOS systems in contact with the alkaline electrolysis system, such as gas-liquid separators, electrolyte pumps, heat exchangers for temperature control of the electrolyte, and filters and piping for electrolyte circulation, are typically made of steel-based materials (carbon steel and stainless steel). Examples can be found in EP 4001464 A1 and DE 4014778 A1.

[0014] In alkaline electrolysis using an aqueous electrolyte, the electrolyte is typically in contact with materials such as steel, particularly carbon steel or stainless steel. Elements present in these steels, such as iron, chromium, molybdenum, and manganese, are leached out by the alkaline electrolyte, resulting in the accumulation of these element ions in the electrolyte to a certain concentration.

[0015] Therefore, these cations accumulate on the surfaces of the cathode and anode of the electrolytic reactor, leading to accelerated catalyst aging. This particularly reduces the electrochemically active surface area of ​​the catalyst. This results in continuous degradation of cell activity, leading to continuous degradation of the electrolytic reactor after a large area is covered by cations. This results in a continuous increase in energy consumption while the amount of gaseous products formed remains constant. The shortened lifespan necessitates the premature replacement of affected cells. Since replacing individual cells in the electrolytic reactor is costly and inconvenient, it is desirable for electrodes and cells to have the longest possible lifespan.

[0016] Another undesirable process in the aforementioned cation deposition is dendrite formation. Dendrite formation is undesirable because when dendrite growth leads to anode-cathode connection, it causes a short circuit within the electrolytic cell. If this occurs, the affected electrolytic cell must be replaced immediately.

[0017] The above problems are particularly relevant in alkaline electrolysis because the leaching rate increases with increasing temperature, and therefore the electrode contamination rate also increases with the operating temperature of the electrolyte.

[0018] Electrode aging occurs more rapidly when electrodes with low active surface area are used.

[0019] Electrolytic cell electrodes have two important characteristic values: geometric surface area and effective surface area. In the case of circular electrodes, the geometric surface area is defined by its diameter. The effective surface area is defined per unit area (e.g., m²). 2 or cm 2 The geometric surface area of ​​a catalyst determines its catalytically active surface area. Depending on the electrode manufacturing method, the active surface area can be many times larger than the geometric surface area. Under constant impurity concentrations in the electrolytic medium and a constant ion deposition rate per unit active electrode surface area, electrodes with smaller active surface areas will experience a faster performance degradation than those with larger active surface areas. Summary of the Invention

[0020] The purpose of this invention is to at least partially overcome the aforementioned disadvantages of the prior art.

[0021] A particular objective of this invention is to avoid or at least limit the accumulation of cations in the electrolyte, thereby avoiding or at least limiting electrode aging in the electrolytic stack due to metal cations. Preferably, aging caused by metal cations such as iron cations, chromium cations, manganese cations, and molybdenum cations is avoided, regardless of their oxidation state.

[0022] The independent claims contribute to at least partially achieving at least one of the aforementioned objectives. The dependent claims provide preferred embodiments that contribute to at least partially achieving at least one of the stated objectives. Preferred embodiments of a component of one category according to the invention are, where applicable, also preferably used for the same name or corresponding component of another corresponding category according to the invention.

[0023] Terms such as “having,” “including,” or “comprising” do not exclude the possibility of other elements, components, etc. The indefinite article “one” does not exclude the possibility of multiple elements.

[0024] One aspect of the present invention provides an electrolysis assembly operating using an alkaline electrolysis medium, the electrolysis assembly comprising a first region and a second region, wherein:

[0025] - The first region includes an electrolytic stack comprising multiple electrolytic cells, wherein the electrolytic stack is adapted to generate a first gaseous product from an alkaline electrolytic medium in the anode region and a second gaseous product from an alkaline electrolytic medium in the cathode region;

[0026] - The second region is fluidly connected to the first region, and the second region includes multiple components, wherein the components of the second region are adapted to discharge an electrolytic medium rich in gaseous products from the first region, introduce an electrolytic medium leaning in gaseous products into the first region, and separate the generated gaseous products from the electrolytic medium, and wherein the components of the second region include at least one piping system and an anode-side gas-liquid separator and a cathode-side gas-liquid separator.

[0027] Its features are,

[0028] The component of the second region has an inner region suitable for direct contact with an alkaline electrolytic medium, wherein the inner region is at least partially formed of a nickel layer, and wherein the nickel layer has a layer thickness of at least 0.1 mm and a nickel content of at least 98% by weight.

[0029] According to the invention, the inner region of the second region is at least partially formed by a nickel layer having a layer thickness of at least 0.1 mm and a high nickel content of at least 98% by weight.

[0030] It has been found that thinner nickel layers do not achieve the desired technical effects. That is, despite the known enhancement in corrosion resistance provided by nickel layers, the catalyst in the electrode has been observed to be continuously poisoned by the aforementioned cations. This is because thinner layers have a higher risk of defects such as porosity, voids, cracks, delamination, or inclusions. Such relatively thin layers typically have a thickness of less than 50 μm. These layers are typically obtained through processes such as electroless nickel plating or electroplating.

[0031] It was also discovered that the nickel layer according to the invention must have a high nickel content of at least 98% by weight. This ensures that the content of non-nickel metals is low enough that any cations of the aforementioned types leaching from the nickel layer do not significantly and adversely affect the lifespan of the electrode and thus the lifespan of the battery.

[0032] Examples of suitable materials for nickel plating are those with identification numbers EN 2.4066 (UNS N02200) and EN 2.4068 (UNS N02201).

[0033] Suitable processes for producing nickel layers include:

[0034] - Lined;

[0035] - Electroplating processes, such as barrel plating, explosion plating, and weld plating;

[0036] - As a solid material, it offers optional subsequent shape fits, force fits, or atomic-level bonding;

[0037] - Casting;

[0038] - Subtractive processing of solid materials; and

[0039] -Cladder.

[0040] The inner region is at least partially formed of a nickel layer. The inner region is the area of ​​a corresponding component of the second region of the electrolysis unit that is adapted to direct contact with the alkaline electrolytic medium. That is, during operation of the electrolysis unit, the inner region is in direct contact with the alkaline electrolytic medium. The inner region can be, for example, the inner surface of a pipe, the electrolytic medium contact surface of a circulating pump or valve, or the inner surface of a gas-liquid separator. This list should not be construed as exhaustive.

[0041] In particular, the inner region defines an area that is in direct contact with the alkaline electrolytic medium and is at least partially formed by a nickel layer.

[0042] The nickel layer has a nickel content of at least 98% by weight. Preferably, the nickel layer has a nickel content of at least 98.0% by weight, or at least 98.5% by weight, or at least 99.0% by weight, or at least 99.5% by weight, or at least 99.6% by weight, or at least 99.7% by weight, or at least 99.8% by weight, or at least 99.9% by weight, or at least 99.95% by weight, or at least 99.99% by weight.

[0043] Preferably, the iron content of the nickel layer is less than 2% by weight, or less than 2.0% by weight, or less than 1.0% by weight, or less than 0.5% by weight, or less than 0.3% by weight, or less than 0.2% by weight, or less than 0.1% by weight, or less than 500 ppm, or less than 100 ppm, or less than 50 ppm, or less than 25 ppm, or less than 10 ppm, or less than 5 ppm, or less than 1 ppm.

[0044] Preferably, the chromium content of the nickel layer is less than 2% by weight, or less than 2.0% by weight, or less than 1.0% by weight, or less than 0.5% by weight, or less than 0.3% by weight, or less than 0.2% by weight, or less than 0.1% by weight, or less than 500 ppm, or less than 100 ppm, or less than 50 ppm, or less than 25 ppm, or less than 10 ppm, or less than 5 ppm, or less than 1 ppm.

[0045] Preferably, the molybdenum content of the nickel layer is less than 2% by weight, or less than 2.0% by weight, or less than 1.0% by weight, or less than 0.5% by weight, or less than 0.3% by weight, or less than 0.2% by weight, or less than 0.1% by weight, or less than 500 ppm, or less than 100 ppm, or less than 50 ppm, or less than 25 ppm, or less than 10 ppm, or less than 5 ppm, or less than 1 ppm.

[0046] Preferably, the manganese content of the nickel layer is less than 2% by weight, or less than 2.0% by weight, or less than 1.0% by weight, or less than 0.5% by weight, or less than 0.3% by weight, or less than 0.2% by weight, or less than 0.1% by weight, or less than 500 ppm, or less than 100 ppm, or less than 50 ppm, or less than 25 ppm, or less than 10 ppm, or less than 5 ppm, or less than 1 ppm.

[0047] The first region of the electrolysis assembly includes an electrolysis stack comprising multiple electrolysis cells. Electrolysis stacks are well known to those skilled in the art. The electrolysis stack includes multiple electrolysis cells arranged in a stacked / layered manner, which are fixed by mechanical equipment.

[0048] An electrolytic reactor comprises an anode region and a cathode region. The anode region should be understood as the entire anode space of the electrolytic cell in the electrolytic reactor. The cathode region should be understood as the entire cathode space of the electrolytic cell in the electrolytic reactor. The anode region preferably produces oxygen as a gaseous product. The cathode region preferably produces hydrogen as a gaseous product.

[0049] The second region is fluidly connected to the first region. This fluid connection allows for the circulation of an electrolyte medium rich in gaseous products and an electrolyte medium leaning in gaseous products between the two regions. An electrolyte medium rich in gaseous products should be specifically understood as a two-phase mixture of the electrolyte medium and the gaseous products generated in the anode or cathode region of the electrolytic reactor. The electrolytic assembly is configured such that this two-phase mixture can be discharged from the first region and introduced into the second region. The electrolytic assembly is also configured such that an electrolyte medium leaning in gaseous products can be discharged from the second region and introduced into the first region. An electrolyte medium leaning in gaseous products should be particularly understood as an electrolyte medium from which the corresponding gaseous products have been separated by gas-liquid separation. It is preferred when the electrolyte medium leaning in gaseous products contains only one liquid phase. An electrolyte medium leaning in gaseous products may still contain a certain amount of dissolved or undissolved gaseous products.

[0050] To achieve the above functions, the second region includes multiple components. At least the second region includes components of a piping system, as well as an anode-side gas-liquid separator and a cathode-side gas-liquid separator. The gas-liquid separators are adapted to separate the gaseous products generated in the first region from the alkaline electrolytic medium. Preferably, the second region includes additional components, particularly at least one pump, at least one cooler for cooling the electrolytic medium, at least one control valve, and at least one sensor. Sensors are, in particular, flow meters, temperature sensors, and pressure sensors. In the context of this invention, transformers and rectifiers are not part of the second region because these electronic components are not suitable for contact with the electrolytic medium. The aforementioned components are not fluidly connected to the electrolytic reactor via the electrolytic medium, but rather electrically connected to the electrolytic reactor.

[0051] Preferably, the electrolysis unit is configured to operate under positive pressure. In this context, the term "positive pressure" should be understood to mean pressure above atmospheric pressure. The electrolysis unit is particularly suitable for operation at absolute pressures of 5 bar to 40 bar, preferably at absolute pressures of 15 bar to 35 bar.

[0052] Preferably, the electrolysis unit is also configured to operate at temperatures above room temperature. Specifically, the electrolysis unit is suitable for operation at temperatures between 40°C and 150°C, preferably between 70°C and 120°C, and more preferably between 70°C and 100°C. In particular, this refers to the temperature of the electrolytic medium at the outlet of the electrolytic reactor at the highest temperature mentioned above.

[0053] In another aspect of the invention, the electrolysis assembly is characterized in that the inner region is partially formed of a nickel layer and partially formed of a metal alloy layer, wherein the metal alloy of the metal alloy layer has an iron content of 10% by weight or less.

[0054] In this embodiment, one sub-region of the inner region is formed of a nickel layer, and another sub-region of the inner region is formed of a metal alloy layer. The metal alloy layer has an iron content of 10% by weight or less.

[0055] The metal alloy layer preferably has a thickness of at least 0.1 mm. Particularly preferably, the metal alloy layer has the same thickness as the nickel layer.

[0056] Optionally, certain sections of the inner region may be without a nickel layer. Metal alloys with an iron content of 10% by weight or less are preferred for these regions. Examples of suitable materials are those with identification numbers UNS N04400, UNS N05500, UNS N06600, UNS N06601, UNS N06625 and UNS N06022.

[0057] Preferably, the metal alloy layer comprises at least one element from the group consisting of:

[0058] -nickel;

[0059] -copper;

[0060] -chromium;

[0061] -molybdenum.

[0062] Therefore, the metal alloy layer preferably comprises a metal alloy containing or composed of the aforementioned metals, and the iron content is 10% by weight or less.

[0063] Suitable processes for producing metal alloy layers include:

[0064] - Lined;

[0065] - Electroplating processes, such as barrel plating, explosion plating, and weld plating;

[0066] - As a solid material, it offers optional subsequent shape fits, force fits, or atomic-level bonding;

[0067] - Casting;

[0068] - Subtractive processing of solid materials; and

[0069] -Cladder.

[0070] Preferably, the metal alloy layer has an iron content of 10.0 wt% or less, or 8.0 wt% or less, or 6.0 wt% or less, or 5.0 wt% or less, or 4.0 wt% or less, or 3.0 wt% or less, or 2.0 wt% or less, or 1.0 wt% or less, or 0.5 wt% or less, or 0.25 wt% or less, or 0.10 wt% or less, or 500 ppm or less, or 250 ppm or less, or 100 ppm or less, or 50 ppm or less, or 10 ppm or less.

[0071] In another aspect of the invention, the electrolytic assembly is characterized in that the inner region is formed of a nickel layer to such an extent that at least 50% of its total surface area is formed of a nickel layer.

[0072] More preferably, the inner region is formed of a nickel layer to such an extent that at least 60% of its total surface area is formed of a nickel layer, or at least 70% of its total surface area is formed of a nickel layer, or at least 80% of its total surface area is formed of a nickel layer, or at least 90% of its total surface area is formed of a nickel layer.

[0073] In another aspect of the invention, the electrolytic assembly is characterized in that the inner region is formed of a nickel layer to such an extent that at least 50% of its total surface area is formed of a nickel layer, and the remaining surface area of ​​the inner region is formed of a metal alloy layer with an iron content of less than 10.0% by weight.

[0074] Preferably, the inner region is formed of a nickel layer to such an extent that at least 60% of its total surface area is formed of a nickel layer, or at least 70% of its total surface area is formed of a nickel layer, or at least 80% of its total surface area is formed of a nickel layer, or at least 90% of its total surface area is formed of a nickel layer, and the corresponding remaining surface area of ​​the inner region is formed of a metal alloy layer with an iron content of less than 10.0% by weight.

[0075] In another aspect of the invention, the electrolytic assembly is characterized in that the nickel layer has a layer thickness of at least 0.2 mm, preferably at least 0.3 mm.

[0076] More preferably, the nickel layer has a thickness of at least 0.4 mm, at least 0.5 mm, at least 0.7 mm, at least 0.9 mm, at least 1.0 cm, at least 1.5 cm, or at least 2.0 cm.

[0077] In another aspect of the invention, the electrolysis assembly is characterized in that the metal alloy layer has a layer thickness of at least 0.2 mm, preferably at least 0.3 mm.

[0078] More preferably, the metal alloy layer has a layer thickness of at least 0.4 mm, at least 0.5 mm, at least 0.7 mm, at least 0.9 mm, at least 1.0 cm, at least 1.5 cm, or at least 2.0 cm.

[0079] In another aspect of the invention, the electrolytic assembly is characterized by a nickel layer covering a metal substrate, wherein the metal substrate is not suitable for direct contact with the alkaline electrolytic medium.

[0080] A nickel layer covers the metal substrate, meaning that during the operation of the electrolysis unit, the nickel layer comes into contact with the alkaline electrolyte in a designated area. The metal substrate is bonded to the nickel layer at least through shape fit, force fit, or atomic-level bonding. The metal substrate is configured not to come into contact with the alkaline electrolyte during the operation of the electrolysis unit.

[0081] Considering the metal base layer, it is preferred when it is formed of carbon steel and / or stainless steel.

[0082] Examples of suitable materials are steels with material designations of 1.0345, 1.0425, 1.0481, 1.0473, 1.0487, 1.0488, 1.4404, 1.4462, 1.5415, or 1.0565.

[0083] In another aspect of the invention, the electrolysis assembly is characterized by a metal alloy layer with an iron content of 10.0% by weight or less covering a metal substrate, wherein the metal substrate is not suitable for direct contact with the alkaline electrolytic medium.

[0084] A metal alloy layer with an iron content of 10.0 wt% or less covers the metal substrate, meaning that during operation of the electrolysis unit, the metal alloy layer contacts the alkaline electrolyte in the corresponding area. The metal substrate is bonded to the metal alloy layer with an iron content of 10.0 wt% or less by at least through shape-fitting, force-fitting, or atomic-level bonding. The metal substrate is configured such that it does not come into contact with the alkaline electrolyte during operation of the electrolysis unit.

[0085] When the metal base layer is formed of carbon steel and / or stainless steel, it is preferred.

[0086] Examples of suitable materials are steels with material designations of 1.0345, 1.0425, 1.0481, 1.0473, 1.0487, 1.0488, 1.4404, 1.4462, 1.5415, or 1.0565.

[0087] In another aspect of the invention, the electrolytic component is characterized in that the nickel layer is not formed on the substrate by a chemical or electrochemical coating process.

[0088] The methods described above typically fail to produce sufficient layer thickness; the nickel produced using these methods usually has a layer thickness of less than 0.1 mm. Therefore, using these methods to produce nickel layers is not preferred.

[0089] In another aspect of the invention, the electrolysis assembly is characterized in that it is adapted to operate using an aqueous electrolysis medium having a hydroxide ion concentration of at least 1 mole of hydroxide ions per liter of the electrolysis medium.

[0090] The preferred electrolyte is an aqueous medium containing hydroxide ions and suitable counter cations, particularly sodium and / or potassium.

[0091] Preferably, the hydroxide ion concentration of the aqueous electrolytic medium is at least 2 moles of hydroxide ions per liter of electrolytic medium, or at least 3 moles of hydroxide ions per liter of electrolytic medium, or at least 4 moles of hydroxide ions per liter of electrolytic medium, or at least 5 moles of hydroxide ions per liter of electrolytic medium, or at least 6 moles of hydroxide ions per liter of electrolytic medium, or at least 6.5 moles of hydroxide ions per liter of electrolytic medium, or at least 6.9 moles of hydroxide ions per liter of electrolytic medium.

[0092] Sodium hydroxide aqueous solution (NaOHaq), and more preferably potassium hydroxide aqueous solution (KOHaq), are used particularly as an electrolyte. Attached Figure Description

[0093] The present invention will now be explained in more detail through exemplary embodiments. The following detailed description is taken with reference to the accompanying drawings, which illustrate specific embodiments of the invention. The following detailed description should not be construed as limiting; the scope of protection of the above aspects and embodiments of the invention is defined by the appended claims.

[0094] In the attached diagram:

[0095] Figure 1 A block flowchart of an electrolysis assembly 1 according to an example of the present invention is shown. Detailed Implementation

[0096] The electrolysis unit 1 includes a first region 21 and a second region 22.

[0097] The second region 22 includes two or more components. Each component in the second region has an inner region (not shown) adapted for direct contact with a strongly alkaline electrolytic medium, where the electrolytic medium is a concentrated aqueous solution of KOH. 90% of the total surface area of ​​this inner region is formed by a nickel layer (not shown). The nickel layer has a thickness of 0.1 mm and a nickel content exceeding 98% by weight. The remaining 10% of the total surface area of ​​the inner region is formed by a metal alloy layer (not shown) with an iron content of 10% by weight or less.

[0098] The first region 21 includes an electrolytic reactor 2 having an anode region 3 and a cathode region 4. The first region 21 is fluidly connected to the second region 22 via pipes 7 and 10 and 11. Pipe 7 supplies the electrolytic reactor 2 with a single-phase electrolyte, i.e., an electrolyte leaning towards gaseous products. Oxygen is produced as the first gaseous product in the anode region 3 of the electrolytic reactor 2. Hydrogen is produced as the second gaseous product in the cathode region 4 of the electrolytic reactor 2. Pipe 10 discharges a two-phase mixture of alkaline electrolyte and oxygen from the anode region 3. Pipe 11 discharges a two-phase mixture of alkaline electrolyte and hydrogen from the cathode region 4.

[0099] The second region 22 includes unit 6, a cathode-side gas-liquid separator 8, and an anode-side gas-liquid separator 9. The second region also includes multiple conduits, specifically conduits 7, 10, 11, and 23. These multiple conduits may belong to the second region 22, even if otherwise manifested as partial conduits. Unit 6 includes at least one cooler and a pump for the alkaline electrolytic medium. The cooled electrolytic medium, lean in gaseous products, is fed to the electrolytic reactor 2 via conduit 7 through unit 6. Conduit 7 is divided into two sections for distributing the electrolytic medium to the anode region 3 and the cathode region 4 of the electrolytic reactor 2.

[0100] The components in the second region 22 can also be described as “heap balance” (BOS) components.

[0101] Other components shown that do not belong to the second region are rectifier 5, oxygen cooler 14, and hydrogen cooler 15. Even though they do not belong to the second region 22 here, these components are often referred to as “balanced stack” (BOS) components.

[0102] Gas-liquid separator 8 separates hydrogen from the alkaline electrolytic medium. The hydrogen-lean electrolytic medium is discharged from gas-liquid separator 8 through pipe 23. Gas-liquid separator 9 separates oxygen from the alkaline electrolytic medium. The oxygen-lean electrolytic medium is discharged from gas-liquid separator 9 through pipe 23. Pipe 23 combines the cathode-side and anode-side electrolytic media containing gaseous products and supplies them to unit 6.

[0103] The first gaseous product (oxygen) separated in gas-liquid separator 9 is supplied to oxygen cooler 14 via oxygen line 12. Oxygen cooler 15 cools and condenses entrained water. The dried oxygen product is discharged via oxygen line 16 and can optionally be further purified and used.

[0104] The second gaseous product (hydrogen) separated in the gas-liquid separator 8 is supplied to the hydrogen cooler 15 via the hydrogen pipeline 13. The hydrogen cooler 15 cools and condenses the entrained water. The dried hydrogen product is discharged via the hydrogen pipeline 17 for further purification and use.

[0105] Rectifier 5 supplies DC power to electrolytic reactor 2, that is, the rectifier is electrically connected to the electrolytic reactor (see the dotted line between components 2 and 5).

[0106] Electrolysis unit 1 also includes so-called “equipment balancing” components 19, 24 and 25.

[0107] Fresh deionized water is supplied to the second zone 22 via deionized water production equipment 19. This compensates for the water consumed in the electrolysis reaction. The deionized water is then supplied to the gas-liquid separator 9 via pipeline 20.

[0108] The cooling water system 24 provides cooling to the separators 8 and 9, the unit 6 and the rectifier 5 via the cooling water piping system 18.

[0109] Transformer 25 converts alternating current from the connected power grid (not shown) into alternating current of appropriate voltage and transmits the alternating current to rectifier 5. Transformer 25 is electrically connected to rectifier 5 (see the dotted line between components 25 and 5).

[0110] List of reference numerals

[0111] 1 Electrolysis Unit

[0112] 2 Electrolytic Reactor

[0113] 3 Anode Region

[0114] 4 Cathode Region

[0115] 5 rectifiers

[0116] 6 units with electrolytic medium cooler and circulating pump

[0117] 7. Piping for single-phase electrolytic media

[0118] 8 Cathode-side gas-liquid separator

[0119] 9 Anode-side gas-liquid separator

[0120] 10. Piping for two-phase mixtures (anode side)

[0121] 11. Piping for two-phase mixtures (cathode side)

[0122] Oxygen pipes 12 and 16

[0123] Hydrogen pipelines 13 and 17

[0124] 14 Oxygen Cooler

[0125] 15 Hydrogen Coolers

[0126] 18 Cooling water piping system

[0127] 19 Deionized Water Production Equipment

[0128] 20 Pipes for deionized water

[0129] 21 First District

[0130] 22 Second Region

[0131] 23 Piping for single-phase electrolytic media

[0132] 24 Cooling water system

[0133] 25 transformer

Claims

1. An electrolytic assembly (1) operating using an alkaline electrolytic medium, the electrolytic assembly comprising a first region (21) and a second region (22), wherein: - The first region (21) includes an electrolytic stack (2) comprising a plurality of electrolytic cells, wherein the electrolytic stack is adapted to generate a first gaseous product from an alkaline electrolytic medium in an anode region (3) and a second gaseous product from an alkaline electrolytic medium in a cathode region (4); - The second region (22) is fluidly connected to the first region (21), and the second region (22) includes a plurality of components, wherein the components of the second region (22) are adapted to discharge an electrolytic medium rich in gaseous products from the first region (21), introduce an electrolytic medium poor in gaseous products into the first region (21), and separate the generated gaseous products from the electrolytic medium, and wherein The components of the second region include at least one piping system (7, 10, 11, 23) and an anode-side gas-liquid separator and a cathode-side gas-liquid separator (8, 9). Its features The component of the second region (22) has an inner region suitable for direct contact with an alkaline electrolytic medium, wherein the inner region is at least partially formed of a nickel layer having a layer thickness of at least 0.1 mm and a nickel content of at least 98% by weight.

2. The electrolysis assembly according to claim 1, wherein, The inner region is partially formed of a nickel layer and partially formed of a metal alloy layer, wherein the metal alloy layer has an iron content of 10% by weight or less.

3. The electrolysis assembly according to claim 1 or 2, wherein, The inner region is formed of a nickel layer to such an extent that at least 50% of its total surface area is formed of a nickel layer.

4. The electrolysis assembly according to claim 2 or 3, wherein, The inner region is formed of a nickel layer to such an extent that at least 50% of its total surface area is formed of a nickel layer, and the remaining surface area of ​​the inner region is formed of a metal alloy layer with an iron content of less than 10.0% by weight.

5. The electrolysis assembly according to any one of the preceding claims, wherein, The nickel layer has a thickness of at least 0.2 mm, preferably at least 0.3 mm.

6. The electrolysis assembly according to any one of the preceding claims, wherein, The nickel layer covers a metal substrate, wherein the metal substrate is not suitable for direct contact with the alkaline electrolytic medium.

7. The electrolysis assembly according to claim 6, wherein, The metal base layer is formed of carbon steel and / or stainless steel.

8. The electrolysis assembly according to any one of claims 2 to 7, wherein, The metal alloy layer, having an iron content of 10.0% by weight or less, covers the metal substrate, wherein the metal substrate is not suitable for direct contact with the alkaline electrolytic medium.

9. The electrolysis assembly according to claim 8, wherein, The metal base layer is formed of carbon steel and / or stainless steel.

10. The electrolysis assembly according to any one of claims 6 to 9, wherein, The nickel layer is not formed on the substrate by a chemical or electrochemical coating process.

11. The electrolysis assembly according to any one of claims 1 to 10, wherein, The electrolysis unit is adapted to operate using an aqueous electrolytic medium having a hydroxide ion concentration of at least 1 mole of hydroxide ions per liter of electrolytic medium.

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